In this study, the protective effect and underlying mechanism of American Ginseng Polysaccharide (AGP) against H2O2-induced oxidative damage in HepG2 cells were investigated based on the Nuclear Factor-erythroid 2-related Factor 2 (Nrf2)/Heme Oxygenase-1 (HO-1) signaling pathway. H2O2 at a concentration of 300 μmol/L was selected for establishing an oxidative damage model of HepG2 cells (cell survival rate: 62.23%), and 320, 640 or 1 280 μg/mL of AGP was given for intervention, and the reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH), and malondialdehyde (MDA) levels in each group of cells were measured separately; the expressions of Nrf2, SOD1, SOD2, HO-1, and CAT proteins in the cells were analyzed by Western blot. The results showed that the AGP treatment had insignificant effect on the proliferation of HepG2 cells, and AGP at the three dose could significantly increase the survival rate of oxidatively damaged HepG2 cells, which were 89.36%, 91.42%, and 91.06%, respectively; The levels of ROS (15.74%, 20.71%, and 25.39%) and MDA content in oxidatively damaged cells were significantly reduced, and the levels of intracellular SOD, GSH, and CAT proteins were effectively elevated; Western blot results showed that AGP could significantly up-regulate the protein expression levels of Nrf2, SOD1, SOD2, HO-1, and CAT (P<0.05, P<0.01). In summary, AGP can ameliorate the oxidative damage in HepG2 cells by regulating the Nrf2/HO-1 signaling pathway. The results of this study can provide more data support for the further development and utilization of AGP.